Reduction drive for drill presses and the like



May 2, 1950 R. E. MCKELVEY 25065514 REDUCTION DRIVE FOR DRILL PRESSES AND THE LIKE Filed March 8, 1946 flIlIllllllIllI/ Ill@ ffjljiz .l

ffice/:fewer jatented May 2, 195.0

UNITED STATESPATENT OFFICE REDUCTION DRIVE FOR DRILL PRESSES AND THE LIKE Robert E. McKelvey, Los Angeles, Calif.

Application March 8, 1946, Serial No. 652,879

7 Claims.

vdirectly on the rotor shaft of the electric motor the speed at which it is driven is governed by the speed of the motor. Most motors supplied for machine tools of this character are designed for use with alternating current and consequently their rotors rotate at relatively high speeds. This necessitates the quill of a drill press to likewise be driven at high speed even though the belt drive between the stepped pulleys is so arranged to drive the quill at the lowest speed. The high speed of rotation of the quill of the conventional drill press frequently is not objectionable in drilling with small drills. However, ifit is desired to drill with large drills vor to A`use the drill press for routing or end-milling purposes the minimum speed at which the, quill can be driven is entirely too high for satisfactory operation.

yAn object of the present invention is to provide a conversion unit that may be readily applied to the electric motor of a drill press, lathe, or similar machine tool which will enable the stepped pulley associated with the motor to be driven at a materially lower speed than the rotor speed of the motor and thus allow the quill of the drill press to be driven at desired lower speeds.

More specifically an object of the invention is to provide a reduction drive for drill presses, lathes, and like machine tools consisting of a bracket applicable to the motor housing and having a countershaft rotatably and adjustably mounted thereon, the countershaft being equipped with sprockets at its ends which in turn are chain-driven by a sprocket mounted on the rotor shaft and chain drive a driven sprocket rotatably mounted on a bushing surrounding the other end of the motor shaft and having the stepped pulley associated with the motor rigidly connected to the driven sprocket` whereby the reduction drive when applied will' occupy a minimum amount of space and will not require alteration of the conventional machine tool.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure l is a perspective view of a drill press illustrating the improved reduction drive as having been applied thereto;

Fig. 2 is 'a sectional view taken substantiallyl upon the line 2-2 upon Fig. 1; and

Fig. 3 is a partial horizontal section ltaken substantially upon the'line 3-3 upon Fig. 2.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the drill press generally indicated at III is of conventional design having an electric motor I I mounted on its column. The quill of the drill press is generally indicated at I2 and carries a stepped pulley I3 at its top. The stepped pulley I3 is driven by an endless belt I4 and in the conventional drill press the belt Id is driven by a stepped pulley mounted on the top of the rotor shaft of motor II. The conversion unit for providing a reduction drive consists of a C-shaped bracket I5, the horizontal arms of which indicated at I6 and Il are apertured to pass over the ends I8 and I9 of the rotor shaft of the motor. These arms are attached to the motor housing such as by screws 20. The vertical portion 2l of the C-shaped bracket is arranged to lie against the outer side of the motor housing.

To this vertical portion there is hingedly con, nected such as bya hinge 22a leaf 23 and this leaf can be adjusted with relation to the bracket by means. of an adjusting screw 24 preferablylongitudinal movement therein. The lower end of the countershaft has a sprocket 30 rigidly fastened thereto. an endless chain 3| from a small sprocket 32 which is applied to the lower end I9 of the shaft of the rotor which in the conventional construction projects downwardly a short distance below i the motor housing. In a similar mannerfthe upper end of the countershaft 28 is equipped with a small sprocket33 over which an endlessv This sprocket is driven byf may be separate and rigidly attached thereto. The endless belt i4 is trained over this pulley.

Y Y drives the sprockets 33 ,and A31'` so 4,that the chain 34 is trained. A hollow bushing 35 is provided having a flange 36 at its bottom which is attached to the upper horizontal arm I6 of the bracket. This Ybushing is slipped over the upper end I8 of the Vrotor shaft and provides a stationary shaft or spindle on which a large sprocket 31 is rotatable and over which the endless chain 34 is trained, 'lhestepped pulley rwhich is l compleme'tit/ary it`0-` thel stepped pulleyv 13,"y isipr'eerably foriied integral With the sprocket T31 but By the improved constructioriitivil-l be: @prelciated that when the motor Il is operated-*its rotor drives the small sprocketyg), theendless chain 3|, and the large sprock'."3il'sY 'that the countershaft 23 is driven at ant'eriallyredcd speed with respect to the speed of rotation owtlie rotor of the motor. The countershaft trn @weinatzcbesfieblyrefinedsteeds fthe uitlt is`not necessary-to r'e ove motor, means providing fai-dr the motor housing, a countershaft rotatably mounted on the bracket, sprockets on the ends of the countershaft disposed opposite ends of the rotor shaft of the motor, a sprocket on one end of the rotor shaft, a chain connecting the sprocket with the sprocket on the adjacent'end of the countershaft, a bushing disposed about the Q therjend of the y rotor straft@J sprocket and pulleyrotatable upo'nfthe bushing, andfa'chain connecting the last inentibid sprocket `vth the sprocket on the other end of the countershaft.

` 2. A reduction drive for drill presses, lathes, and ith' .dike-:comprising a motor,a sprocket secured to'ne end of the rotor shaft of the motor, a counl tershai't mounted on the side of the kmotor for ro- 'ttihlabbt'xs parallel Vto the rotor shaft, a "sprocket 101i the countershaft chain driven from the mentioned sprocket, a sprocket and pulleyhuted for rotation about the other end ofutherotor shaft, and chain and sprocket means tijriaflpuiieyimqiiiitd forfitatioii' abbutitiie @tif-er Y 14. "A'fieductibiidrive for iditiutpresss,f-iathes, aad the like, `"teniet ising Aiii tor, fa '-b-siaped bracket applieiit'o" "the ifiotor Having Vits A-arias dispdsd over theefids or therefor-fighetta, `fi'ieiif hingedly f mounted 'upon the bracket, fa 'countersueftrotatabiy'munteu upon therieaf for Arota"- tioii'aboiit'an iaxisipairauei vto the4 rotor Eshaft, niear'sifor'aldju'sting the leaf with relation to tle bracket vto adjust the countersiiaft toward Aari-ii slaftfandsaidiplley.

M0 the rotor-'shaft off-the f the meer: e .albeit 5 6 the length of the motor and 'rotatably mounted REFERENCES CITED on the bracket means wlth lts axls parallel to the rotor shaft of the motor means at least a The following references are of record in the part of which is mounted on one end of the counfue of 17h15 Patent: tershaft adapted to provide a drive between said 5 UNITED STATES PATENTS one end of the countershaft and one end of the rotor shaft of the motor, a pulley supported by Number Name Date 1,693,757 Kaptuller Dec. 4, 1928 the bracket means so as to be rotatable about 2,176,572 Hedgpeth Oct. 17, 1939 the other end of the rotor shaft. and means pro- 2 299 921 M ers Oct 27 1942 'ding a drive between the other end of the 10 y V1 2,430,798 Alexander Nov. 11, 1947 countershaft and said pulley.

ROBERT E. MCKELVEY. 

